Net guns are non-lethal anti-riot devices for use by police officers, soldiers and civilians (hereinafter referred collectively to as users) in capturing targets, such as robbers, enemies, and terrorists. Conventional net guns are capable of firing a catching net at a target to entangle the target and thus capture the target without causing serious harm to the target. However, in the situation where a target is in possession of a weapon, such as a handgun, it could be too late for a conventional net gun to fire the catching net at the target in order for the target to succumb, not to mention that the conventional net gun does not serve any defensive purpose.